The present invention concerns a system for axially locking the end of a long component such as a shaft or column in a host component such as a sleeve. The lock becomes effective when the shaft component fits axially and is fully engaged in the second component.
To assist the reader, reference will be made below to the preferred application of the invention, which is the automotive equipment industry.
More specifically, this type of axial locking problem is encountered for example when a steering column is fitted to a switch bracket arranged between the column and the steering wheel. In this type of application, the problems requiring a solution can be simply defined:
It must be possible to assemble and dismantle these parts easily, preferably using a single tool, or even without a tool;
When these components are secured to each other, the lock must be positive, preventing all possible relative movements and conserving its mechanical characteristics for the longest possible duration.
In connection with the above example these requirements can be described in a less generic fashion, namely the fitting of a switch bracket to the upper part of a column and their axial and rotational locking, preferably by means of an adjustable device, if one is used, accessible on the front of the switch bracket, ie facing the steering wheel.
Locking may also be obtained automatically, ie without any adjustable devices, notably by means of a device using a return force, according to a method widely employed.
Systems for fitting steering columns to switch brackets already exist using reliefs located at the ends of the columns, enabling the latter to be clipped into slots provided for this purpose in the switch brackets. The method used is based on the elasticity of the materials, and therefore on a spring effect applied to the contact areas, which are deformed and then return to their original positions as soon as they are able to do so, ie when they are opposite the slots.
However, in a locking system as outlined above the lock must not only be effective after assembly, but also easy to dismantle.
The existing systems referred to above are not easy to dismantle, since the steering column clips into the switch bracket peripherally, generally presenting a rotational symmetry. It can therefore only be dismantled simultaneously around the entire periphery, which can prove to be a delicate operation and/or one requiring a special tool.
Generally, in configurations such as these, axial locking is also obtained by means which at the same time ensure rotational locking, as is the case in the existing solution referred to above, hence the difficulties in terms of dismantling.